1. Field of the Invention
This invention relates generally to dispersions of carbon nanotubes in polymer matrices. It relates particularly to dispersions of carbon nanotubes in polymer matrices employing donor-acceptor bonding, which dispersions exhibit long term stability and are suitable for the preparation of nanocomposites.
2. Description of Related Art
Carbon nanotubes, which are now well-known in the art, are being employed in, and proposed for a number of applications which take advantage of their unique combination of physical properties, e.g., their strength and weight. For example, state-of-the-art lightweight aerospace structures are presently built from graphite fiber composites. It is proposed that with their impressive combination of properties, carbon nanotube nanocomposites will surpass the performance of present day conventional graphite fiber composites by providing both load-bearing and sensing functionalities in vehicle structures.
However, this is not possible until problems associated with the use of carbon nanotubes are resolved. In particular, prior efforts to achieve a high degree of dispersion of carbon nanotubes in a polymer matrix have been fraught with difficulty, due primarily to the high affinity of carbon nanotubes for each other (i.e., their tendency to agglomerate in bundles) and their rather weak interaction with common polymers.
Prior efforts, using a combination of mechanical mixing, sonication, and in situ polymerization techniques, have been found wanting, in that they have yielded dispersions which are kinetically stable, but which tend to phase separate over a period of days or weeks, indicating thermodynamic instability.